How to select a good Speaker Cable

Mr. kiwipeter

For 3 m and DF = 320, a #1 awg is recommended (you can go also with #0 awg).

b4icu,

Glad to see are you are well and offering useful free advice.

You may recall I used your DIY 0 AWG cable (relatively flexible thin strand welder's cable) to connect Pass Lab 250.5 to Magnepan MGIIIa's.  Fantastic results.

I have changed the amp to a Devialet 120 Class D integrated.  It loves you cables.  My simplistic system consists of an Auralic Aries connected to the 120, driving the Maggies.  In addition, I use the pre-out/electronic crossover to connect a 12" Velodyne FSX.  The room is 35x25x14ft.  All electronics are power by a Yeti 1000 drawing less than 50 watts.

I noted that you referenced Class D amplification above.  Would you be so kind as to share your information as to why your designs work so well with Class D amps.  I am assuming that you have not already addressed this issue.  I have not read all of the posts on this thread.

Best Regards,

J

Hi Mr. keppertup

I remember you well. One of the guys who implemented my cable advice and was happy with the results:

"Pass Lab 250.5 with Magnepan III's.

I replaced DIY 5 foot 16 AWG silver ladder line.  Have previously used a variety of commercial Helix design, solid flat wire and braided multi-stranded wires insulated and in multiple sleeves. All 12 AWG, 5 to 8 foot length.  Costs ranged from $400 to $2,000.

Dear b4icu57,

I purchased 25 feet of 0 AWG form a supplier on eBay for $45 ($12 shipping) and four brass (supposedly gold plated) battery connectors ($7.49).

I constructed four five foot cables in just over one hour.  Battery connectors were converted to spades with a cold chisel and wire cutters, cable was cut with a hacksaw and insulation stripped with the hacksaw.  Spades were connected to Pass Labs 250.5 terminals (PL does not supply banana plug receptacles).  I attached banana plugs to a two inch piece of silver plated 8 AWG wire.  I hollowed out a holle in 0 AWG wire with a punch and did not remove insulation.  I then inserted the stripped 8 AWG wire in hole and secured the assembly with a hose clamp around the insulation at the cable’s end.

The cables were attached to my thirty year old modified MG IIIa’s.  

The results are stunning.  The amount of undistorted energy filling the room, is jaw dropping.  I keep turning up the volume to levels that previously irritated my ears, and experience no irritation.  In the modified lyrics of B.B. King, “The shrill is gone.”  My wife is hearing new detail in cuts she has listened to many times before.

In my case, b4icu57, you were absolutely correct, thank you (except for the part of you doubting ribbon speakers would be improved with installation of your design).  I can’t wait to try the cables in one of my other systems that employs cone speakers.

I am sure every case is different.  Nevertheless, I encourage other hobbyist to test your theories.

Thank you for your generosity and patience.
All good wishes."

Well, Class-D, tend to have a Spec. of high to very high DF (Dumping Factor). It is in the thousands...

As DF is a representation of Ro (output Resistance) and equals to 8/Ro, a DF of 4000 (common to D-Class Amps) is 0.002 ohms.

If I compare it to your PASS Labs 250, with a DF of 150, it's Ro equals to:

0.053 ohms. In other words. it's 26 times lower Ro, of better DF !

How it is achieved: 

D-Class is a high speed switching power device. It uses some H-FET or equivalent high power and very low ON resistance, between the power rails and the output. That's the DF or Ro are coming from.

For the Devialet 120 (replaced an older model called 110, and now they are at 140...) I'd found no Spec. regarding it's DF. I'll try to contact them later today to ask their technical support about the DF figure.

As It was on my last thread, it is also now (Physics didn't change), the higher the DF (same cables length) the importance of thick cables grows.

The other parameter that I use in my calculations, is the cable length. 

I assume the length is the same: 6 ft.?

Hi
Here is Mr.  Hiroko (Devialet) replay:

Hiroko (Devialet)

Jul 29, 2020, 12:04 PM GMT+2

Dear Michael,

Thank you very much for reaching out to us today.

I have received an answer from our engineer.
Please kindly be informed that the Spect of DF of the 120 is 8000.

Hope it helps your inquiry.

Have a great day!
Kind Regards,

Hiroko | Customer service & support Devialet

8000 is a very high figure for DF.
The highest I've ever seen!!!

For the calculations, you wont like it at all...
It calls for 25x 0 awg! @ 6ft. long cable.
This is impossible and very thick.
I would say:
1. Go as thick as you possible can.
2. Some  Devialet amps can be used as monoblock.
If you could afford that, a very short cable (10'' or less) would make it better, using still a thick cable (maybe #000 awg or 4x0 awg).

It might be that a second answer will arrive directly from their main office in Paris, with whom I spoke on the phone today.
If they provide a different figue, I'll update you.

Dear b4icu,

Thank you very much for the generous investment of your valuable time.

I look forward to hearing if Devialet in Paris has any additional information.

I will experiment with doubling up the 0 AWG six foot lengths.  You haven't been wrong yet, so I expect interesting results. 

Best regards,

J